Electronic devices such as smart phones can suffer by being in bright light or low light during a scene change or during a camera launch. While in these conditions, a default or current setting for automatic exposure control (AEC) of the camera will generally result in an overblown image or a dark image, respectively, for a humanly perceptible period of time until the AEC settings converge. These overblown or dark images are particularly captured when taking videos. Other automatic camera control settings that depend on AEC, such as automatic white balance (AWB), are also delayed by slow AEC convergence. White balance in digital photography means adjusting colors so that the image looks more natural. In particular, AWB needs AEC to settle first in order for AWB to get proper exposure index or lux index for different light source weighting interpolations.
For camera launch or activation among different light intensities, different exposure integration times should ideally be used for fast convergence. Thus, for bright light condition, a short exposure should be used to avoid the image being overblown. For low light, a long exposure should be used to avoid a dark image. However, the generally-known camera only knows light condition (bright or dim) after camera launch from referencing statistics (“stats”) collected by the camera. Thus, generally-known cameras using one fixed initial value that is subsequently tunable when launching the camera suffer the overblown or dark pictures issue. For a generally-known camera chipset, the AEC convergence employs a system of adjusting the exposure after two or three frames to allow time for the previous setting to take effect. With commonly experienced lighting conditions, these chipsets need at least 18 frames to converge, with some scenes requiring more than 30 frames to converge. Speeding up the frame rate to reduce the AEC convergence time is generally not a satisfactory solution since the current camera image is previewed on a user interface (UI). The high frame rate limits the amount of digital image processing that can be accomplished for each frame and less sensor integration time, resulting in a low-quality image. Thus generally-known electronic devices experience slow AEC convergence at camera launch that impacts a key performance indicator (KPI) of camera launch to readiness and overblown or dark preview pictures during scene change under different light intensities, which negatively impact user experience.